Datacentres provide a controlled operating environment for Information and Communication Technology (ICT) equipment. The ever increasing demand for productivity gains achievable through ICT, and the continuous rapid improvement in processing and storage densities of ICT equipment, has made it increasingly difficult for legacy datacentre designs and construction practices to keep pace with the provision of space, power and cooling necessary to support ICT operations.
Traditionally, datacentres have been housed in conventional brick and mortar facilities that remain relatively static in terms of floor space capacity, power capacity and cooling capacity over their 15 to 20 year life spans. Expanding the space, power and cooling capacity of legacy datacentres often requires lengthy building development applications and approvals, custom engineering and site-specific construction projects involving expensive skilled contractors.
Datacentres are typically constructed to be initially over-sized so that capacity requirements can grow into the facilities. This is “capital expenditure” inefficient. It is also operationally inefficient because of the need to cool (control the environment) for a large area.
Modern datacentre facilities, require specialised expertise that is not readily available from the general construction industry. Today's datacentres now need to be able to rapidly expand (or contract) their floor space capacity, power supply capacity or cooling capacity or a combination of all of these to optimally support dynamic ICT requirements.
Datacentre infrastructure is typically categorised into one of two categories, namely “ICT Infrastructure” or “Site Infrastructure”. ICT infrastructure is use to perform operations such as data transfer, manipulation and processing and includes equipment such as computer server equipment, data storage equipment and data communication equipment. Site Infrastructure includes all the supporting plant and equipment such as Uninterruptible Power Supplies (UPS), Power Distribution Units (PDU), back-up generators, Computer Room Air Conditioning (CRAC), chillers, cooling towers, fire detection and suppression equipment and general lighting.
Attempts have been made to utilise portable modular units, some the size of ISO shipping containers as datacentre modular units. Some examples of these include International Publications WO2007/139560(Google, Inc.) and WO2008/033921(Sun Microsystem, Inc) and US Patent Appln publication No. 2008/0094797(Cogliotore et al.).
Attempts have been made to retrofit standard ISO shipping containers. This provides a less than optimal solution in many circumstances. The internal air temperature of a standard intermodal shipping container that is exposed to the sun can rise significantly. If a standard intermodal shipping container were used to house ICT equipment, then a considerable amount of energy would be required to condition the air temperature resulting from exposure to the sun.
Previous attempts to containerise datacentre facilities have failed to deliver a system that provides an expandable floor space for the “data hall”. In this specification “data hall” is the area in which ICT infrasrtucture/hardware is housed.
While the majority of ICT infrastructure can be installed into a standard 19-inch rack, some equipment does not. Therefore it is important that if containerised units are used for the purpose of a “data hall”, it is advantageous to be able to expand floor space to accommodate all varieties of ICT equipment, otherwise containerised systems will be limited in their application.
In existing prior art datacentres, cooling and humidifying surplus space is very inefficient and therefore removing surplus floor space is likely to be an important energy efficiency strategy for datacentres of the future.
In the prior art, attempts to containerise datacentre facilities have tended to focus on cramming IT infrastructure into shipping containers, and have given little or inadequate consideration to important “Site Infrastructure” elements and general environmental considerations. Previous attempts have failed to deliver a complete “Site Infrastructure” solution. Prior art containerised solutions still require a substantial amount of custom engineering and on-site project effort to deploy the solution, and so do not fully realise the benefits associated with prefabrication and assembly line manufacturing.
A comprehensive system that includes all necessary datacentre “Site Infrastructure” components in the form of prefabricated, factory assembled modules in the form of “data hall modules” will minimize (or eliminate) complexity and costs associated with large construction projects. However, it is necessary that a comprehensive system exist, otherwise a large construction project will still be required to fill the gaps, and the advantages of prefabrication will be diluted.
A comprehensive Site Infrastructure approach to containerised datacentres gives rise to better overall energy utilisation and management practices. Waste energy in one part of the Site Infrastructure solution may be harnessed to do useful work in another part of the Site Infrastructure solution. A complete site infrastructure solution also gives rise to better overall energy management, enabling end-to-end energy monitoring and control system to achievable real time optimisation of energy usage.
It is also proposed to utilise containerised datacentres (or data hall modular units) to include site infrastructure such as specialised “chiller equipment”, with the aim of developing a complete containerised infrastructure solution for datacentres.
A conventional electric chiller operates on the heat pump principle, where heat is removed from the datacentre and dumped to the outside air. On hot days, the surrounding air is often warmer than the desired temperature for the datacentre cabinets, so heat must be “pumped” using external energy, usually electricity.
A heat pump works by circulating a refrigerant fluid in a closed circuit, through an evaporator, a pump (compressor), a condenser and an expansion valve. The configuration of a prior art “conventional electric chiller” is shown in FIG. 14. The various temperatures of the refrigerant fluid shown at different locations of the circuit in FIG. 14 are for example purposes only and may vary.
Heat is absorbed (i.e. cooling effect is produced) in the evaporator 4 by the evaporation of a refrigerant fluid at low pressure. The refrigerant vapour is then compressed by an electric pump (compressor) 6 to higher pressure and temperature, consuming electricity. In addition to the heat absorbed by evaporator 4, most of the energy consumed by compressor 6 also ends up in the compressed refrigerant fluid resulting in high temperature at the outlet of compressor 6.
The heat must then be discarded from the system to the surroundings in condenser 2. Compressed vapour is cooled by forcing air past condenser 2, analogous to the operation of a car radiator. Thus the vapour coming in to condenser 2 must be hotter than the surrounding air if it is to lose heat. As such, compressor 6 will need to draw more electricity on hot days to provide sufficient condensing temperature to allow heat to be rejected through condenser 2. The higher temperature requirement on hot days manifests as higher pressure at the compressor outlet, hence the increased compression effort required at compressor 6.
At the outlet of condenser 2, the vapour has condensed to liquid at high pressure. The expansion valve drops the liquid pressure before the liquid returns to the evaporator for further cooling.
The performance of a heat pump is defined by a figure of merit called the co-efficient of performance (COP). The COP is usually defined by the ratio of the amount of heat pumped from the evaporator (the cooling effect) to the amount of energy put into the system. For an electric chiller, the COP is defined by the cooling effect in kW divided by the electrical power consumption of the compressor, also in kW. A high COP is associated with a good heat pump.
The COP can be greater than one and this is a common source of confusion. One might clarify this by understanding that the cold is not created; the energy is used only to move heat. A typical 40 kW electric heat pump might have a COP of 4.5.
Since there is a direct relationship between electricity consumption and greenhouse gas emissions, there is an implicit relationship between COP and greenhouse gas emissions.
Care is required in the use of the COP. The rated value is only valid for the rated conditions and any departure in the operating conditions will have significant ramifications for COP. For example, load operation under partial load or changes to the evaporating or condensing temperatures.
The COP can be misleading for other reasons, particularly when comparing electrically driven systems to heat driven systems. In the latter case, customers usually place a higher value on the electrical energy they purchase rather than the waste heat that drives the cooling cycle. Thus a redefined COP expression is warranted. Three definitions are often used:
Thermodynamic COP (COPth)—The thermodynamic COP defined as the ratio of cooling effect to total energy required to produce that cooling effect (as above). For a standard heat pump, this might be 4.5
Electrical COP (COPel)—The electrical COP is the ratio of cooling effect to electrical energy required. For conventional heat pumps, this is the same as COPth.
Primary energy (COPpe)—The primary energy COP is the ratio of cooling effect to primary energy consumed including the supply chain (e.g. the coal mine and power station). For a conventional heat pump in Australia, this is typically 0.85.
The COPpe is the preferred definition since it relates most closely to the problems facing heat pump air conditioners, namely greenhouse gas emissions and electricity grid loading.
The COP, electricity consumption and greenhouse gas emissions of a heat pump is largely dictated by the temperature lift between its evaporator and condenser. Thus, a reduction in condensing temperature is most beneficial to reducing greenhouse gas emissions.
For a chiller employed in a containerised datacentre (or data hall), a reduction in condensing temperature of one degree Celsius is equivalent to a reduction of 0.41 kW of compressor electricity consumption.
The idea of operating the electric chiller at night when the ambient temperature is lower than the daytime, and then storing the cooing capacity for later use, would be an obvious approach. However, feasibility studies suggest that the logistics and expense of the extra facilities would not be workable.
In order to reduce energy consumption it is necessary to unload the condenser when it is most under stress. However, in order to do so in a containerised datacentre it must importantly be achieved using both minimal extra equipment and minimal additional space.
The ejector or jet pump principle has been used for some time to produce vacuum for industrial processes using low grade heat. Steam ejectors were used up until the 1930s for cooling purposes, but went out of favour when higher performance vapour compression units became available. Steam driven ejectors up to several hundred kilowatts cooling capacity were not uncommon wherever waste steam or heat was available. Since there is, only one moving part (a pump) in an ejector heat pump, they would typically run for twenty years with no maintenance. Most of the effort in ejector research today is targeted towards coupling ejectors to solar collectors.
Whilst the COPth of standard heat pump (electric chiller) might be about 4.5, ejector heat pumps typically have a COPth of 0.6.
Whilst the COPel of a standard heat pump (electric chiller) might the same as the COPth, but ejector heat cycles COPel typically range from 15-50.
Whilst the COPpe of a standard heat pump (electric chiller) in Australia is typically about 0.85, an ejector heat pump COPpe is about 12-45. As such, based on COPpe use of an ejector heat pump cycle is desirable.
One object of the present invention is to provide a data hall module, and method of constructing a data hall infrastructure system that overcomes at least one of the problems associated with the prior art.
Another object of the present invention is to provide a method, apparatus and system that overcomes at least one of the problems associated with the cooling of containerised datacentres (data hall modules). The present invention achieves this by utilising thermal powered compressor (or ejector) technology.